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CUARTERLY GRIGUN6 WATER MOMTORING REPORT ata W.Kettleman,[AGI,"ifornla For a complete site history, a description of site conditions, regional and local geology, hydrology, a description of subsurface conditions, a summarization of analytical results related to previous investigation and a further definition of the term"thief port"please refer to Aegis Site Assessment-Monitbring Well Installation Results Report,"dated March 26, 1991 and"Pre-Tank Replacement Site Assessment Results Report,"dated October 1989. 3.0 QUARTERLY MONITORING RESULTS 3.1 Groundwater Level Measurement Data obtained during the January 1991 monthly water level measurements is summarized in Table 1. This information includes the date, depth to groundwater measurement, reference elevation at the top of the well casing and the groundwater elevation for the three on site wells. Each measurement was made from the top of the well casing with a Seattle Slope Indicator and referenced to sea level. A groundwater gradient and flow direction for the subiect site was established based upon the groundwater elevations derived from the field measurements. The groundwater flows direction has been established in a southeasterly direction as shown on the ground-water table contour map (Figure 2). The groundwater gradient was measured as 0.0014 ft/ft. Refer to Regis' Standard Operating Procedures (SOP), in Appendix B number 12 for protocol relating to field measurements. 3.2 Groundwater Sam le Collection and Labpra!2CLAnalysis - The groundwater samples were collected on January 16, 1991. The three monitoring wells were purged and groundwater samples were collected according to the Aegis' standard operating procedure (SOP-7)included l,n the attachments. The field data sheets are included in Appendix C. The water samples from eanh well were collected in 40-m1 VOA vials and one-liter glass-amber bottles. The samples were immediately placed on ice in a cooler and delivered under chain-of-custody to Coast-to-Coast Analytical Services -- (CCAS) in San Luis Obispo, California. The water samples for MW-1, 2, a au 3 were analyzed for fuel fingerprint which includes: ^� a) total purgeable petroleum hydrocarbons as gasoline (f"PPH-G); b) benzene, ethylbenzene, toluene, and total xylenes (BTEX); c) 1,2-Dbromoethane (EDB); d) 1,2- Dichloroethane (EDC) and e) total lead. The laboratory analyses is as follows: the Fuel Fingerprint Analysis by extraction with EPA method 5030 (purge and trap) and analyzed by CAL DHS DRAFT TPH (modified) and EPA method 8240 (GC/MS)for,constituents a) - - - - 09.0138.RPT — 2 —